Structure and method for inserting inserts in stationary blade of gas turbine

ABSTRACT

An insert inserting structure and a method for enabling a stationary blade of a gas turbine to withstand high temperatures of even 1500 C. in order to realize a 150° C. class gas turbine is provided. In a stationary blade of a gas turbine including a hollow opening (2, 3, 4) into which an insert (5, 6, 7) having a plurality of cooling-air ejecting apertures (8) formed in a side wall thereof is inserted to thereby cool wall surfaces of said hollow opening (2, 3, 4) with cooling air ejected from said cooling-air ejecting apertures (8), a structure for inserting an insert in a stationary blade of a gas turbine, comprising a pair of seal plates (9a, . . . , 9f) disposed on side walls of said insert (5, 6, 7) and two grooves (11a, . . . , 11f) disposed on said wall surfaces of said hollow opening (2, 3, 4) so as to receive fittingly said seal plates (9a, . . . , 9f), respectively, wherein at least one (11b, 11c, 11d, 11e) of said two grooves (11a, . . . , 11f) is provided in a seal block (10b, 10c, 10d, 10e) mounted on said wall surface.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present invention relates to a stationary blade of a gas turbine andin particular to a structure and a method for inserting inserts intohollow openings provided in the stationary blade of a gas turbine forcooling same.

2. Description of the Related Art

The internal portion of a stationary blade of a conventional gas turbineis provided with a front hollow opening 2, an intermediate hollowopening 3 and a rear hollow opening 4, as is shown in FIG. 4. Insertedinto the hollow openings 2, 3 and 4 are a front insert 5, anintermediate insert 6 and a rear insert 7, respectively, each of whichis formed as a hollow member corresponding to the hollow opening. Theinserts 5, 6 and 7 are each formed of a thin plate provided with anumber of cooling-air ejecting apertures 8 each having a diameter of 0.1to 0.5 mm.

In the gas-turbine stationary blade 1 of the structure mentioned above,cooling air is supplied to the hollow portions of the inserts 5, 6 and 7during driving of the gas turbine, wherein the cooling air passesthrough the cooling-air ejecting apertures 8 formed in the inserts 5, 6and 7 to impinge onto the wall surfaces of the hollow openings 2, 3 and4 formed in the internal portion of the gas-turbine stationary blade 1to thereby cool the gas-turbine stationary blade 1 from the inside.

When cooling the gas-turbine stationary blade 1 from the inside in thismanner, the cooling-air ejecting apertures 8 formed in the inserts 5, 6and 7 function as orifices because of the small diameters thereof tothereby constrict the flow of the cooling air. Thus, the cooling of thegas-turbine stationary blade 1 with the cooling air can be performedefficiently and effectively.

In the conventional gas-turbine stationary blade, the wall surfaces ofeach of the hollow openings 2, 3 and 4 are provided with three or moreprojecting portions 20, as are shown in FIG. 5, wherein each of theinserts 5, 6 and 7 is held by the projecting portions 20 to allow thecooling air to flow through the space defined between the wall surfaceand the insert. The inserts 5, 6 and 7 have fitting structures such thatthey fit snugly with the projecting portions 20. Moreover, theprojecting portions 20 are finished by machining so as to conform to theouter dimensions of the inserts 5, 6 and 7 so that the inserts can bereliably held.

Gas turbines have hereinbefore been operated with a combustion gashaving a temperature of 1500° C. or less. Recently, however, effortshave been made to develop a gas turbine which can be operated with acombustion gas having a temperature of 1500° C. so as to enhance theefficiency of the gas turbine. In order to allow a 1500° C. class gasturbine to be employed in practical applications, the inserts have to befabricated using a plate of Hastelloy with a thickness of 0.5 mm.

However, when the same fitting structures as the conventional ones, forholding the individual inserts 5, 6 and 7 within the hollow openings 2,3 and 4 are adopted it is difficult to form the projection portions 20by machining, thus making it difficult to properly position the inserts.Consequently, some portions of the gas-turbine stationary blade 1 maynot be able to be sufficiently cooled to withstand the high temperature1500° C. combustion gas.

OBJECT OF THE INVENTION

Accordingly, in order to solve the problems mentioned above, it is anobject of the present invention to provide a structure and a method forinserting inserts in a stationary blade of a gas turbine, wherebyinsertion of the inserts in the hollow openings of the gas-turbinestationary blade makes it possible for the stationary blade to bepositively sufficiently cooled so as to withstand the high temperature1500° C. combustion gas.

SUMMARY OF THE INVENTION

To achieve the objects mentioned above, the present invention featuresthe characteristic arrangements mentioned below.

(1) In a stationary blade of a gas turbine including a hollow openinginto which an insert having a plurality of cooling-air ejectingapertures formed in a side wall thereof is inserted to thereby cool wallsurfaces of said hollow opening with cooling air jets ejected from saidcooling-air ejecting apertures, the present invention proposes astructure for inserting the insert in the stationary blade of the gasturbine, the structure comprising a pair of seal plates disposed on sidewalls of said insert and two grooves provided in said wall surfaces ofsaid hollow opening so as to fittingly receive said seal plates,respectively, wherein at least one of said two grooves is provided in aseal block mounted on said wall surface.

As is apparent from the above, the thin seal plates each having athickness comparable to that of the insert can be mounted on the sidewall of the insert, while the thick seal blocks each having a thicknesscomparable to the wall of the stationary blade are mounted on the wallsurface of the stationary blade. Thus, the occurrence of strain uponprovisional mounting by spot welding and final mounting by brazing canbe prevented, and thus each of the inserts can be mounted with highprecision.

Thus, insertion of the inserts into the hollow openings, which canensure positive cooling of the gas-turbine stationary blade, can beachieved, whereby the gas-turbine stationary blade can withstand thehigh temperature 1500° C. combustion gas, thus making it possible torealize a 1500° C. class gas turbine.

(2) The present invention teaches a method of inserting an insert in astationary blade of a gas turbine, the method comprising the steps ofmounting at least one seal block on a wall surface of a hollow openingof a gas-turbine stationary blade, forming grooves in said seal blockand said wall surface, respectively, mounting a pair of seal plates on aside wall of the insert, and inserting said insert into said hollowopening while fitting said pair of seal plates into said grooves.

As is apparent from the above, since the seal block is mounted on thewall surface of the hollow opening of the gas-turbine stationary bladeand the grooves are thereafter formed by machining, it is possible tomount the seal block to the gas-turbine stationary blade of thestructure (1) proposed by the present invention as previously described,and at the same time, it is possible to mount the seal plates on theinsert and form the grooves with high precision.

Thus, the insertion of the insert into the hollow opening, which ensurespositive cooling of the gas-turbine stationary blade, can be achieved,as described previously in conjunction with the feature (1) of thepresent invention, whereby a 1500° C. class gas turbine can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is a plan view of a stationary blade of a gas turbine accordingto an embodiment of the present invention, FIG. 1b is a viewillustrating the fitting between a projecting portion and a seal platein the structure shown in FIG. 1a, FIG. 1c is a view illustrating thefitting between a seal block and a seal plate (with a groove width of0.4 mm) in the structure shown in FIG. 1a, FIG. 1d is a viewillustrating the fitting between a seal block and a seal plate (with agroove width of 0.6 mm) in the structure shown in FIG. 1a, and FIG. 1eis a view illustrating the fitting between a wall surface portion and aseal plate in the structure shown in FIG. 1i a.

FIG. 2a is a view illustrating a seal plate in a state for mounting in aseal block in the structure according to the above embodiment, and FIG.2b is a view for illustrating the seal block in a state in which theseal plate is to be mounted in the seal block.

FIG. 3 is a flow-chart illustrating a method of inserting an insert in ahollow opening of a stationary blade of a gas turbine according to theembodiment.

FIG. 4a is a view generally showing a conventional stationary blade of agas turbine, and FIG. 4b is a view illustrating insertion of insertsinto the hollow openings.

FIG. 5 is a plan view showing a conventional stationary blade of a gasturbine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described in detail in conjunction withwhat are presently considered as preferred embodiments for carrying outthe present invention with reference to the appended drawings.

In the following description, like reference numerals designate likeparts throughout the drawings. Furthermore, also in the followingdescription, it is to be understood that such terms as "right", "left","top", "bottom" and the like are words of convenience and are not to beconstrued as limiting terms.

Embodiment 1

A structure for inserting inserts in a stationary blade of a gas turbineaccording to an embodiment of the present invention will be describedwith reference to FIGS. 1 and 2.

The embodiment of the present invention now under consideration isapplied to a stationary blade 1 of a 1500° C. gas turbine in which afront hollow opening 2, an intermediate hollow opening 3 and a rearhollow opening 4 are provided, wherein a front insert 5, an intermediateinsert 6 and a rear insert 7 each having a thickness of 0.5 mm andformed of hollow structures corresponding to the hollow openings 2, 3and 4, respectively, are inserted into the respective hollow openings.

The structure for inserting the inserts in the stationary blade of thegas turbine according to the instant embodiment shown in FIGS. 1 and 2is implemented as follows. The front hollow opening 2 has a wall surfaceformed at a front edge side with a projecting portion 10a having agroove 11a (see FIG. 1a) while a seal block 10b having a groove 11b isformed in a rib portion adjacent to the intermediate hollow opening 3(see FIG. 1d). On the other hand, the front insert 5 to be inserted intothe front hollow opening 2 has side walls provided with seal plates 9aand 9b at positions corresponding to those of the grooves 11a and 11bformed, respectively, in the projecting portion 10a and the seal block10b which are provided in the front hollow opening 2 so that the sealplates 9a and 9b can be inserted into the grooves (see FIGS. 1a and 1d).

Further, the intermediate hollow opening 3 has a wall surface formedwith a projecting portion 10c having a groove 11c in the rib portionadjacent to the front hollow opening 2 (see FIG. 1c) while a seal block10d having a groove 11d is formed in a rib portion adjacent to the rearhollow opening 4 (see FIG. 1d). On the other hand, the intermediateinsert 6 to be inserted into the intermediate hollow opening 3 has sidewalls provided with seal plates 9c and 9d at positions corresponding tothose of the grooves 11c and 11d formed, respectively, in the sealblocks 10c and 10d which are provided in the intermediate hollow opening3 so that the seal plates 9c and 9d can be inserted into the grooves(see FIGS. 1c and 1d).

Furthermore, the rear hollow opening 4 has a wall surface formed with aseal block 10e having a groove 11e in the rib portion adjacent to theintermediate hollow opening 3 (see FIG. 1d) while a wall surface portion10f having a groove 11f is provided at the rear edge side (see FIG. 1e).On the other hand, the rear insert 7 to be inserted into the rear hollowopening 4 has side walls provided with seal plates 9e and 9f atpositions corresponding to those of the grooves 11e and 11f formed,respectively, in the seal block 10e and the wall surface portion 10fprovided in the rear hollow opening 4 so that the seal plates 9e and 9fcan be inserted into the grooves (see FIGS. 1d and 1e).

Each of the seal plates 9a, . . . , 9e is shaped approximately in anL-shape form in order to facilitate the shaping process and thealignment thereof, wherein one leg thereof is fixedly secured to each ofthe inserts and the other leg is capable of being inserted into thecorresponding groove of the seal block and the like formed in the wallsurface of the hollow openings. The seal plate 9f of the rear insert 7is however bent at an obtuse angle so as to correspond to the groove 11fformed in the wall surface portion 10f of the rear hollow opening 4, ascan be seen in FIG. 1e. Nevertheless, the angle at which the seal plate9f is bent can be changed as desired depending on the position at whichthe groove 11f is formed.

The seal blocks 10b, . . . , 10e are fixedly secured to respective sealblock seats which are formed by machining corresponding wall surfaces ofthe respective hollow openings 2, 3 and 4, of the stationary blade 1.

Moreover, each of the seal plates 9a, . . . , 9f has a thickness of 0.25mm, whereas the groove width of the grooves 11a, 11c and 11f is 0.4 mmand that of the grooves 11b, lid and lie is 0.6 mm.

The reason the thickness of the seal plates 9a, . . . , 9f is selectedto be 0.25 mm can be explained by the fact that the above thickness iscomparable to that of the inserts 5, 6 and 7, selected to be 0.5 mm, andthat upon spot welding the seal plates 9a, . . . , 9f to the inserts 5,6 and 7, respectively, in the state in which the seal plates 9a, . . . ,9f are fitted in the grooves 11a, . . . , 9f, high precision can beassured for the seal plates 9a, . . . , 9f which are provisionallysecured through spot welding.

Moreover, by selecting the groove width of the grooves 11a, 11c and 11fto be 0.4 mm while selecting the groove width of the grooves 11b, 11dand 11e to be 0.6 mm, each of the inserts 5, 6 and 7 can be easilyinserted into the corresponding hollow openings 2, 3 and 4, and leakageof the cooling air in the individual grooves 11a, . . . , 111f can berestrained within a predetermined range because one of the pair of sealplates 9a, . . . , 9f mounted on each of the inserts 5, 6 and 7 isinserted in the groove of 0.4 mm width while the other is inserted inthe groove having the width of 0.6 mm.

Next, the description will be directed to a method of inserting theinserts 5, 6 and 7 into the stationary blade 1 of the gas turbineaccording to the instant embodiment with reference to FIG. 3.

Starting from a casting of the gas-turbine stationary blade 1 beingsupplied (step 1), the seal block seats are formed by machining atlocations where the seal blocks 10b, 10c, 10d and 10e are to be mounted,respectively (step 2).

Subsuquently, the seal blocks 10b, . . . , 10e are tacked orprovisionally mounted on corresponding machined seal block seats by spotwelding and then permanently secured by brazing (step 3). Thepermanently secured seal blocks 10b, 10c, 10d and 10e then undergomachining through a wire cutting process together with the projectingportion 10a and the wall surface portion 10f, whereby the grooves 11a, .. . , 11f are formed (step 4).

After the seal plates 9a, . . . , 9f are fitted in the respectivegrooves 11a, . . . , 11f, the inserts 5, 6 and 7 are inserted into thecorresponding hollow openings 2, 3 and 4. After the insertion of theinserts, the seal plates 9a, . . . , 9f are provisionally attached tothe inserts 5, 6 and 7 by spot welding. After completion of the spotwelding, the inserts 5, 6 and 7 are withdrawn from the correspondinghollow openings 2, 3 and 4, whereupon the seal plates 9a, . . . , 9f arepermanently secured through brazing (step 5).

After completion of the permanent attachment of the seal plates 9a, . .. , 9f to the inserts 5, 6 and 7, the individual inserts 5, 6 and 7 arereinserted into the corresponding hollow openings 2, 3 and 4, whilefitting the seal plates 9a, . . . , 9f in the corresponding grooves 11a,. . . , 11f (step 6). Thus, the work of inserting the inserts into thehollow openings of the gas-turbine stationary blade 1 is completed.

In conjunction with the mounting process described above, it is notedthat both the wall structure of the gas-turbine stationary blade 1 andthe seal blocks 10b, . . . , 10e are thick. Thus, when the seal blocks10b, . . . , 10e are attached provisionally to the respective seal blockseats of the gas-turbine stationary blade 1 by spot welding and/or whenthe groove machining is performed on the projecting portion 10a, theseal blocks 10b, . . . , 10e and the wall surface portion 10f throughthe wire cutting process, strain does not occur, whereby the grooves11a, . . . , 11f can be formed with high precision.

Furthermore, since the thickness of the seal plates 9a, . . . , 9f is0.25 mm, which is substantially comparable to that of the 0.5 mm inserts5, 6 and 7 as described hereinbefore, and since the seal plates 9a, . .. , 9f are fitted into the grooves 11a, . . . , 11f, respectively, andthereafter spot welding is performed, precision can be ensured for theseal plates 9a, . . . , 9f mounted provisionally on the inserts 5, 6 and7 by spot welding.

Moreover, since a pair of seal plates are mounted on each of the inserts5, 6 and 7, and since the groove into which one seal plate of each pairof the seal plates is inserted has the width of 0.4 mm while the widthof the groove into which the other seal plate is inserted is 0.6 mm, theinserts 5, 6 and 7 can be easily inserted into the hollow openings 2, 3and 4, respectively, and leakage of the cooling air in the grooves 11a,. . . , 11f can be suppressed to within a predetermined range.

By virtue of the arrangement according to the instant embodiment,precise positioning of the inserts within the respective hollow openingsof the gas-turbine stationary blade can be realized while ensuringpositive internal cooling of the gas-turbine stationary blade by virtueof the structure in which the seal blocks and the seal plates areemployed when the inserts are inserted into the hollow openings of thegas-turbine stationary blade. Thus, the gas-turbine stationary blade canwithstand the high temperature combustion gas of 1500° C., and hence a1500° C. class gas turbine can be realized.

In the structure for inserting inserts in a stationary blade of a gasturbine according to the present invention, wherein the inserts eachhaving a plurality of cooling-air ejecting apertures formed in the sidewalls are inserted into the respective hollow openings of thegas-turbine stationary blade, and in which each of the inserts isprovided with a pair of seal plates disposed on the side walls thereof,and a pair of grooves which fittingly receive the seal plates,respectively, are disposed in the wall surface of the hollow opening,and at least one of the two grooves is provided in the seal blockmounted on the above-mentioned wall surface, it is possible to mount thethin seal plate having a thickness comparable to that of the insert onthe insert, while the thick seal blocks each having a thicknesscomparable to the wall thickness of the gas-turbine stationary blade canbe mounted on the gas-turbine stationary blade. Thus, the occurrence ofstrain upon mounting can be prevented. Consequently, positioning of theinserts relative to the hollow openings of the gas-turbine stationaryblade can be performed with high accuracy. Thus, insertion of theinserts into the hollow openings for ensuring positive cooling of thegas-turbine stationary blade can be achieved, making it possible torealize a 1500° C. class gas turbine.

Furthermore, owing to the method which includes the steps of mounting atleast one seal block on the wall surface of the hollow opening of thegas-turbine stationary blade, forming the groove in each seal block andthe above-mentioned wall surface, mounting a pair of seal plates on theside wall of the insert, and inserting the above-mentioned insert intothe above-mentioned hollow opening while fitting the pair of seal platesin the corresponding grooves, the grooves can be formed with higherprecision, whereby the possibility of realizing the 1500° C .class gasturbine can further be increased.

In the foregoing, the embodiment of the present invention which isconsidered preferable at present and alternative embodiments thereofhave been described in detail with reference to the drawings. It should,however, be noted that the present invention is never restricted tothese embodiments but other applications and modifications of the cooledstationary blade for the gas turbine can be easily conceived andrealized by those skilled in the art without departing from spirit andscope of the present invention.

What is claimed is:
 1. In a stationary blade of a gas turbine including a hollow opening into which an insert having a plurality of cooling-air ejecting apertures formed in a side wall thereof is inserted to thereby cool wall surfaces of said hollow opening with cooling air jets ejected from said cooling-air ejecting apertures, a structure for inserting an insert in the stationary blade of the gas turbine, comprising a pair of seal plates disposed on side walls of said inserts and two grooves disposed on said wall surfaces of said hollow opening so as to fittingly receive said seal plates, respectively, wherein at least one of said two grooves is provided in a seal block mounted on said wall surface.
 2. A structure for inserting an insert in a stationary blade of a gas turbine as set forth in claim 1, wherein said pair of seal plates are disposed on said side walls of said insert in opposition to each other.
 3. A structure for inserting an insert in a stationary blade of a gas turbine as set forth in claim 2, wherein said hollow opening includes a front hollow opening, an intermediate hollow opening and a rear hollow opening, and wherein said insert includes a front insert, an intermediate insert and a rear insert.
 4. A structure for inserting an insert in a stationary blade of a gas turbine as set forth in claim 3, wherein said other groove disposed in said front hollow opening is provided in a projecting portion formed in said wall surface of said front hollow opening.
 5. A structure for inserting an insert in a stationary blade of a gas turbine as set forth in claim 3, wherein said two grooves disposed in said intermediate hollow opening are provided in said seal blocks, respectively.
 6. A method of inserting an insert in a stationary blade of a gas turbine, comprising the steps of mounting at least one seal block on a wall surface of a hollow opening of a gas-turbine stationary blade, forming grooves in said seal block and said wall surface, respectively, mounting a pair of seal plates on a side wall of an insert, and inserting said insert into said hollow opening while fitting said pair of seal plates in said corresponding grooves.
 7. A method of inserting an insert in a stationary blade of a gas turbine as set forth in claim 6, wherein the step of mounting the seal block on the wall surface of the hollow opening of said gas-turbine stationary blade includes the steps of machining a seal block seat on said wall surface at a location at which said seal block is to be mounted on said gas-turbine stationary blade, attaching provisionally the seal block on said seal block seat by spot welding, and permanently mounting said seal block to said seal block seat by brazing.
 8. A method of inserting an insert in a stationary blade of a gas turbine as set forth in claim 6, wherein the step of mounting the pair of seal plates on the side walls of said insert includes the steps of fitting said pair of seal plates in said grooves, respectively, inserting said insert into said hollow opening, attaching provisionally said pair of seal plates onto said insert by spot welding, withdrawing said insert from said hollow opening, and permanently mounting said pair of seal plates on said insert by brazing. 